5 Important Facts of Circuit Switching in Computer Networks

Do you want to really interested to know about circuit switching in computer networks then this post is for you. Today we are going to discuss about circuit switching. In this post, I will talk about some such important things about Circuit Switching Networks which will be very helpful for you from the exam point of view. So let’s get started.

Circuit switching was generally designed for telephone networks. This was at a time when the OSI model, the TCP/IP model, was not used at all. Today we are using computer networks. In these computer networks, every computer is connected to each other through a network and shares data.

Generally, speaking about computers, we have personal computer, laptops, mobile, etc. The network that existed before this computer network was the telephone network. In this telephone network, the trick we used to physically connect every device is called circuit switching.

What is Circuit Switching in COmputer Network?

Circuit switching is a network connection in which connection is given between two points through a physical path. It was commonly used in telephone networks. In this, data is transmitted in 3 phases. First, the connection is established, then the data transfer takes place and finally, the connection is disconnected.

A feature of this switching circuit is that it establishes the connection at a fixed data rate, which is to be operated at the same data rate by the source and destination user. This switching technology is less advanced than another switching. That’s why it is not used so much nowadays. And one more reason is that in today’s time everyone has started using smartphones and many advanced technologies have also come. So this circuit-switching technology lags a bit behind.

Let us know about some important points of circuit switching.

5 Important Facts of Circuit Switching in Computer Network

Physical layer

Circuit switching mainly works at the physical layer. As we know, in OSI or TCP/IP models, data is sent from one layer to another and finally reaches the user. But there is no such thing in this. This switching works in the physical layer, it is said that, because it establishes the physical connection between two subscribers.

In this, when you make a connection with another user through the telephone line and only then you are able to talk in one flow. In this process, when you make a connection with a user, it first goes to the nearest telephone exchange. After that, the connection is made from that exchange to the nearest exchange of the destination user and finally goes to the destination user from the destination exchange.

Generally, there is a dedicated path is made for this connection. Although the source and destination users are not connected as point-to-point, it still looks like a dedicated connection. Once a connection is made, the data flow continues until you disconnect the connection.

Contagious flow

The meaning of this contagious flow is that once you make a connection with another user. Then the data that is transferred or received is in a continuous form.

If we talk about the layer, then the data that comes from the application layer has to be divided into segments. Then it has to divide into packets and then divide the packets into frames. But there is nothing like this in it. In this, data is transferred directly between two users in a continuous flow.

One important thing in this is that, when the data keeps on transmitting, it does not go out of the data flow. This means that when you send some data to another user, that data is received by the next user in the same sequence. In this, the data used to be here and there.

For example: When you say how are you by calling another user. In the same way, that user listens to the sentences you have spoken in the same order. There is no sequence change in the data at the time of transmission.

No Header

The header is used to indicate the source and destination address. But in this circuit switching, no packets are used for transmission. Therefore, the header is not used in it. As soon as the setup is done in the circuit switching, the data is transmitted and no header is required.

When data is transferred, a dedicated path is reserved. At that time no other user can use the same path. No header will be required in this, so data transfer will continue in one line only.


The efficiency in circuit switching is low because one path is reserved. Let’s say you started talking with one of your friends. After talking for some time, you asked to hold for 2 minutes. You didn’t cut that call and put it on the site. Through that, the connection remains active and the bandwidth is reserved in it.

In that connection, you are not sending any data or receiving anything. But still, you keep that path reserved. Therefore, efficiency gets reduced.


In this switching circuit, sending some messages is not delayed. This is because there is no other node or router between the dedicated path from the source to the destination. In the other switching techniques, there are routers in between the path.

These routers store the packets then verify them and after that send them to the destination. But there is no store and forward method is apply because no router is in this switching technique. That’s why there is a lot of work done at the time of sending the data.

Phases of Circuit Switching

In this circuit-switching technique, data transmission takes place in 3 phases. We will know this from circuit switching diagram

  • Circuit establishment or Setup phase
  • Data transfer
  • Circuit Disconnection

Circuit establishment or Setup phase

Circuit Switching Networks connection establishment

Creating a dedicated link between two endpoints in this phase is called connection establishment. The time it takes to establish this connection is called setup time. According to the diagram, if T1 wants to send some message to T2, the first exchange between them will provide a dedicated path to both of them. After that T1 and T2 will be able to communicate with each other.

Data transfer

Circuit Switching Networks Data transfer

When the connection from the source to the destination is established, then the data transmission starts. An important thing in this is that when the source places its data in that dedicated path, that time is called transmission time. After that, the amount of time that the data travels from the source to the destination is called Progression Time. There is very little delay in this data transmission.

Circuit Disconnection

Circuit Switching Networks Circuit disconnect

When the sending and receiving of data between the source and destination stops, then only that dedicated connection has to be cut. The time taken to cut this connection is called teardown time.

Advantages and disadvantages of circuit switching


  • One of the biggest advantages of circuit-switched networks is the reserve of a dedicated communication channel circuit between the source and the destination.
  • In this, there is no delay in sending the message due to no node or router being installed between the source and the destination.
  • In circuit switching networks, direct data is sent and received. No packets are used in this. For this reason, the header is not needed and the source and destination can communicate directly.
  • The best part of this circuit-switching network is that when data is sent, only in the sequence in which the sender data is sent, the receiver receives that data.


  • Circuit switching technology being an old technology, it may have been used by telephone networks only. If we talk about it for email, WhatsApp, and other connections then it can’t be there.
  • In this switching network, the path from source to destination is reserved at the time of data transmission. For this reason, efficiency is required in it.
  • It is more expensive than other switching techniques because it works in the physical layer.

Also Read


If said, this circuit switching network usually works in telephone networks. In this, a physical medium is used to transmit data in the network. Therefore a dedicated path is given from the source to the destination for data transmission.

I hope you all must have known about circuit switching in computer networks, Phases and the advantages and disadvantages of circuit switching after reading this article Circuit Switching Network. Still, if you have any kind of doubt regarding this post, then you can tell us by commenting. We will do our best to solve your problem

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